Beaches and other land forms that surround large bodies of water have always been subjected to severe erosion caused by the currents and waves. Erosion can lead to massive amounts of beachfronts disappearing, leaving higher ground exposed to the full energy of waves. The exposure to wave energy can lead to further erosion of the higher ground and possible damage to adjacent structures. Many attempts have been made to prevent such erosion from occurring. Marine structures have been developed to dissipate the power of the waves and shield the shoreline from waves. However, many of these structures, such as jetties and sea walls, have their own shortcomings. Solid structures, like jetties, are constructed of rocks and concrete blocks and are expensive to build and install. Additionally, such structures are massive in size, can further disrupt the environment, and can be visually unappealing. Also, the solid nature of these structures may lead to further erosion; the force of the waves is redirected, and not dissipated, to the bottom of the structures, causing erosion at the base of the solid structure.
Soft structures, like ballast-filled tubes, have been developed to solve many of the problems mentioned above. In order to withstand the constant pounding of waves, these tubes should be manufactured from a liquid permeable material having sufficient tensile strength, seam strength, and wear resistance. Geotextiles are one type of material that fit such criteria. When constructed, the geotextile tubes are filled with a ballast material, such as sand slurry and concrete. While the tubes create a wave barrier, the permeable nature of the tubes, in combination with the fill material, absorb much of the energy generated by crashing waves, leading to a greater reduction in erosion above and below the geotextile tube. The geotextile tubes also provide a much more cost-effective solution than solid structures.
While the geotextile tubes may be a better alternative than the solid structures mentioned above, their current construction and installation have several drawbacks. The size of geotextile tubes is constrained based upon the tensile strength of the geotextile as well as the stress limits of the seams. Therefore, in most cases, marine structures require the installation of multiple geotextile tubes. However, the construction of geotextile tubes does not aid in their modularity. Traditionally, each tube is manufactured from one continuous piece of fabric by folding the fabric in half and then securing the adjacent edges together. When filled with slurry, the ends of the geotextile become pinched, forming a geotextile tube 10 with sloping ends 12, as shown in FIG. 1. Since the geotextile tubes 10 do not have a uniform cross-section across their length, placing them end to end does not result in a barrier with a uniform height and level top, which is essential to form an effective barrier against wave energy. Additionally, many marine structures require a greater height than that provided by one tube, which requires tubes to being stacked on one another. When tubes are placed over the junctions of the sloping ends, the upper tubes sag into the spaces between the lower tubes, creating a top surface with non-uniform height.
To combat this shortcoming, the tapered ends 12 of the traditional geotextile tubes 10 are overlapped with one another, as shown in FIG. 2, creating additional problems. By overlapping, each geotextile tube's effective length is diminished, requiring more geotextile tubes to be used to form the needed marine structure at a greater cost. Second, gaps can be created between the tubes by the overlapping, hindering the overall performance of the marine structure. In order to achieve a gap-free junction and a structure with a relatively continuous flat top, smaller geotextile tubes 20, as shown in FIG. 3, are used to fill the gaps created by the overlapping, which increases installation costs. Third, the overlapping increases the difficulty of anchoring and securing the ends of the geotextile tubes during installation, which can increase the chances of compromising the integrity of the junctions formed between adjacent geotextile tubes. Unsecured overlapping in stacked multiple tubes can further compromise the structural integrity of the overall protective structure and may be unsightly.
Therefore, there is a need for geotextile tubes that when placed end to end form gapless junctions. Additionally, there is a need for geotextile tubes that may be filled to a uniform height.